NXCALS-1339 Adds test cases for EntityClient
#Merge request template @acc-logging-team - please have a look for approval.
This MR is about testing our declerative feign configuration (via annotations) for the NXCALS service, http requesters.
It comes with the introduction of a basic wiremock configuration, to stup the actual endpoints and simulate a fake target for administering those requests and validate their behaviour based on some well defined expectations.
Currently only the EntityClient behaviour is coved by the effort provided on this MR.
Edited by Grigorios Avgitidis